tools/nolibc/types: make FD_SETSIZE configurable

The macro was hard-coded to 256 but it's common to see it redefined.
Let's support this and make sure we always allocate enough entries for
the cases where it wouldn't be multiple of 32.

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/include/nolibc/types.h

@@ -45,7 +45,9 @@
 #define DT_SOCK        0xc
 
 /* commonly an fd_set represents 256 FDs */
+#ifndef FD_SETSIZE
 #define FD_SETSIZE     256
+#endif
 
 /* Special FD used by all the *at functions */
 #ifndef AT_FDCWD
@@ -72,7 +74,7 @@
 
 /* for select() */
 typedef struct {
-	uint32_t fd32[FD_SETSIZE / 32];
+	uint32_t fd32[(FD_SETSIZE + 31) / 32];
 } fd_set;
 
 #define FD_CLR(fd, set) do {                                            \
@@ -101,7 +103,7 @@ typedef struct {
 #define FD_ZERO(set) do {                                               \
 		fd_set *__set = (set);                                  \
 		int __idx;                                              \
-		for (__idx = 0; __idx < FD_SETSIZE / 32; __idx ++)      \
+		for (__idx = 0; __idx < (FD_SETSIZE+31) / 32; __idx ++) \
 			__set->fd32[__idx] = 0;                         \
 	} while (0)